Flexible and transparent gas sensor based on mos2 and method for manufacturing the same

Abstract

A gas sensor includes: an insulating substrate; a gas sensing portion immobilized on the substrate and comprising MoS 2 flakes containing metal porphyrin; and a Pair of electrodes formed at both ends of the MoS 2 flakes of the gas sensing portion so as to be spaced apart from each other. When MoS 2 flakes are functionalized using cobalt tetraphenylporphyrin as metal porphyrin, the sensitivities thereof to benzene and toluene are significantly increased.

What is claimed is: 
     
         1 . A gas sensor comprising:
 an insulating substrate;   a gas sensing portion immobilized on the substrate and comprising MoS 2  flakes containing metal porphyrin; and   a pair of electrodes formed at both ends of the MoS 2  flakes of the gas sensing portion so as to be spaced apart from each other.   
     
     
         2 . The gas sensor of  claim 1 , wherein the gas sensing portion is formed of a MoS 2  cluster consisting of a plurality of the MoS 2  flakes. 
     
     
         3 . The gas sensor of  claim 2 , wherein the pair of electrodes are formed at both ends of the gas sensing portion so as to be spaced apart from each other at a distance at which they commonly come in contact with one or more of the MoS 2  flakes. 
     
     
         4 . The gas sensor of  claim 3 , wherein the pair of electrodes is spaced apart from each other at a distance equal to half or less of the average length of the MoS 2  flakes. 
     
     
         5 . The gas sensor of  claim 1 , wherein the substrate is made of a flexible and transparent material. 
     
     
         6 . The gas sensor of  claim 1 , wherein the metal porphyrin is cobalt tetraphenylporphyrin (Co-TPP). 
     
     
         7 . The gas sensor of  claim 6 , wherein the gas sensing portion has an increased sensitivity (ΔR/R 0 ) to benzene or toluene compared to a gas sensing portion formed of pristine MoS 2  flakes containing no cobalt tetraphenylporphyrin. 
     
     
         8 . The gas sensor of  claim 7 , wherein the sensitivity (ΔR/R 0 ) of the gas sensing portion is at least 2 times higher to benzene and 30% higher to toluene. 
     
     
         9 . A method for manufacturing a gas sensor, comprising the steps of:
 (a) mixing a solution containing a plurality of MoS 2  flakes with a metal porphyrin-containing solution to prepare a mixture solution;   (b) Placing droplets of the mixture solution on an insulating substrate, and drying the placed droplets, thereby forming a gas sensing portion; and   (c) forming a pair of electrodes at both ends of the gas sensing so as to be spaced apart from each other at a distance at which they commonly come in contact with one or more of the MoS 2  flakes.   
     
     
         10 . The method of  claim 9 , wherein the pair of electrodes is formed so as to be spaced apart from each other at a distance equal to half or less of the average length of the MoS 2  flakes. 
     
     
         11 . The method of  claim 10 , wherein the pair of electrodes are formed at both ends of the gas sensing portion in any direction. 
     
     
         12 . The method of  claim 9 , wherein the substrate is made of a flexible and transparent material. 
     
     
         13 . The method of  claim 9 , wherein the metal porphyrin is cobalt tetraphenylporphyrin (Co-TPP), and the gas sensing portion has an increased sensitivity to benzene or toluene compared to a gas sensing portion formed of a pristine MoS 2  cluster containing no cobalt tetraphenylporphyrin.